Wang Dawei, Zhi Xiyang, Zhang Wei, Yin Zhongke, Jiang Shikai, Niu Ruize
Appl Opt. 2018 Oct 20;57(30):9096-9105. doi: 10.1364/AO.57.009096.
In this paper, we present a model that analyzes the influence of the temperature on the modulation transfer function (MTF) of an infrared membrane diffraction optical system. Based on the physical imaging mechanism of diffractive optical systems, the imaging characteristics of the diffraction optical system are characterized by using diffraction efficiency. Then we establish the corresponding calculation model and MTF analysis model based on scalar diffraction theory. In particular, considering the material properties of flexible membrane optical elements and thermal environment effect, the Zernike polynomials are used to establish the thickness distribution model of the membrane diffractive optical components combined with the finite element analysis. After that, we modify the MTF calculation model of diffraction optical system and accordingly propose the model of the infrared membrane diffraction optical system. Finally, we present some experimental results for a 2-m infrared membrane diffraction optical system. The results show that when the temperature is -40°C and wavelength band is 80 nm at the center field of view, the diffraction efficiency is reduced to 81%, and MTF at 75 l p/mm is reduced to 0.12. And when the temperature is -40°C at edge field of view, the efficiency at center wavelength is reduced to 71%, and MTF at 75 l p/mm is reduced to 0.02. The established model and method can be used to estimate the imaging performance of a space infrared membrane diffractive telescope and provide theoretical guidance for the processing algorithm and imaging system design.
在本文中，我们提出了一个模型，该模型分析温度对红外薄膜衍射光学系统调制传递函数（MTF）的影响。基于衍射光学系统的物理成像机制，利用衍射效率来表征衍射光学系统的成像特性。然后我们基于标量衍射理论建立了相应的计算模型和MTF分析模型。特别地，考虑到柔性薄膜光学元件的材料特性和热环境效应，结合有限元分析，使用泽尼克多项式建立薄膜衍射光学元件的厚度分布模型。之后，我们修正了衍射光学系统的MTF计算模型，并据此提出了红外薄膜衍射光学系统模型。最后，我们给出了一个2米红外薄膜衍射光学系统的一些实验结果。结果表明，当温度为-40°C且在中心视场的波长带为80纳米时，衍射效率降低到81%，75线对/毫米处的MTF降低到0.12。而当温度在边缘视场为-40°C时，中心波长处的效率降低到71%，75线对/毫米处的MTF降低到0.02。所建立的模型和方法可用于估计空间红外薄膜衍射望远镜的成像性能，并为处理算法和成像系统设计提供理论指导。
